A plant cytorhabdovirus modulates locomotor activity of insect vectors to enhance virus transmission

Transmission of many plant viruses relies on phloem-feeding insect vectors. However, how plant viruses directly modulate insect behavior is largely unknown. Barley yellow striate mosaic virus (BYSMV) is transmitted by the small brown planthopper (SBPH, Laodelphax striatellus). Here, we show that BYSMV infects the central nervous system (CNS) of SBPHs, induces insect hyperactivity, and prolongs phloem feeding duration. The BYSMV accessory protein P6 interacts with the COP9 signalosome subunit 5 (LsCSN5) of SBPHs and suppresses LsCSN5-regulated de-neddylation from the Cullin 1 (CUL1), hereby inhibiting CUL1-based E3 ligases-mediated degradation of the circadian clock protein Timeless (TIM). Thus, virus infection or knockdown of LsCSN5 compromises TIM oscillation and induces high insect locomotor activity for transmission. Additionally, expression of BYSMV P6 in the CNS of transgenic Drosophila melanogaster disturbs circadian rhythm and induces high locomotor activity. Together, our results suggest the molecular mechanisms whereby BYSMV modulates locomotor activity of insect vectors for transmission. Most plant viruses are transmitted by insect vectors in finely regulatory mechanisms. Here, the authors show that a plant rhabdovirus can modify circadian rhythm of its insect vectors and enhances locomotor activity for efficient transmission.

Automated summary

This study reveals that the barley yellow striate mosaic virus infects the central nervous system of its insect vector, leading to hyperactivity and prolonged feeding duration. The virus's accessory protein P6 interacts with a specific subunit of the insect vector, inhibiting the degradation of the circadian clock protein Timeless. Furthermore, expression of P6 in fruit flies disrupts circadian rhythm and induces high locomotor activity.